Brakes are tricky.
Mercedes and several other companies change the brake fluid on a regular schedule as part of their scheduled maintenance.
When I saw this many years ago on my car, I asked why. I was told that contaminants and moisture will build up in the fluid and eventually damage the wheel cylinders and master cylinder.

Sounded good to me, so the next time I took my Ford truck in for service, I asked them to flush the brakes.
They looked at me like I was nuts. So, I told them never mind why, just do it and I would pay for it.

I wound up having to bleed them myself twice to get a good pedal back and shortly after I had to replace the master cylinder.

That was about 1979 or so. Today is even trickier. Several of the antilock braking systems can be seriously screwed up by unusual pressure differences between brake lines. A friend of mine replaced a caliper and when bleeding the system got a piston overcentered in the antilock system and had to replace it. $$

Also, for anyone out there who bleeds your brakes after a line break or a cylinder replacement on a vehicle that is over a couple of years old, Go ahead and buy a new master cylinder. Its almost certain you will have to replace it either right after you bleed them, or within a week or so.

Because for all the time it was on your truck, the master cylinder piston traveled about the same distance. It never had to go to the far end of the cylinder.
When you bleed the brakes, you usually bottom out the piston. If the fluid has not been changed for a while, ( veering back on topic<g>) that part of the cylinder is corroded or rusted slightly or a lot.
This will damage the seals of the piston, and after a little while, you will notice when sitting at a red light, the pedal will slowly sink to the floor as the fluid creeps past the seals.

Now, does that mean you should never flush your brake system. No, actually it means you should do it often enough that the cylinder does not get corroded. But, since almost everyone reading this is like me and has not flushed it recently,
( actually I have, since I just replaced all the lines on my truck with stainless.
Had to replace the master cylinder too<g>)
We need to flush it smart.

The only way I know of that avoids damage to everything is a pressure flusher. I have not seen one lately, but I know they are still out there.
Its basically a tank of brake fluid with a pressure source, a hose and an adapter that replaces the top of the master cylinder.
You put small hoses on the bleeders which you stick in small jars of brake fluid and then open all the bleeders.

The pressure flusher pumps clean fluid into the master cylinder through the system and out the hoses.
When it all runs clean, you close the bleeders and put the top of the master cylinder back on.
Of course, you want to suck most of the old fluid out of the master cylinder and replace it with clean before you start so as to minimize the amount of dirty fluid you pump through.

This way the master cylinder never has to be bottomed out, and any antilock brake systems never see anything unusual.

Having said all that, if your truck does have an antilock braking system, I would double check with a shop manual to make sure it does not have some weird requirements.

As for the pressure bleeder, if you have several friends with trucks, it would be fairly cheap to go in and buy one together with adapters for everybody's vehicles.

J.</g></g>

 

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I think they even have one now where the attatchment screws/clicks right onto the Ford master cylinder in place of your cap. I used to use it with the "universal" adapter where you secured it with a chain and wingnuts. Still works extremely well.

-Jim

 

I know we're getting off subject here, but this is serious stuff, maintaining our Rangers!!!!!

Well here is a thread with a link to a nice boling point graph & easy to read tutorial on brake fluid.
https://www.ford-trucks.com/forums/s...d.php?t=366396

I use a one man brake bleeder & Motorcraft Dot-3 fluid to flush my brake fluid every two to three years. The Motorcraft fluid is good stuff, with a very high dry boiling point, a good value for the money, imo.

Just be sure to take your time & don't let the brake master cylinder fluid level get low & ingest air in the system & especialy the ABS motor, or you'll likely end up at the Dealer or a brake shop paying for them to get the air out with a vacuum system.
I begin bleeding at the RR, LR, RF then LF.
The power steering fluid oxidizes just like tranny fluid, so I change mine every time I do the tranny full fluid change out!!!!
Read through this thread, for how I do the P/S.
https://www.ford-trucks.com/forums/s...d.php?t=486850

If your of a mind to save some money & do a full tranny fluid change out yourself, look here, for how I do that myself. With some help, you could do even easier & faster!!!!
https://www.ford-trucks.com/forums/s...d.php?t=494164

Let us know what you decide to do & how it goes.